In the design of packaging for integrated circuits (ICs), a die (having an integrated circuit thereon) is electrically and physically connected to a package. The package has top side conductors, a body portion, and bottom side conductors.
FIG. 1 shows an example of a die 20 and a package 22, wherein the die is a “flip chip” with an interconnect medium 24 (i.e., solder bumps, balls, posts, etc.) thereon, and the package has top side conductors 26, such as pads, for electrical connection to the die, and bottom side conductors 28 for electrical connection with a printed circuit board (PCB), an IC socket, or the like. The bottom side conductors 28 can be in the form of, for example, metallized pads, pins, balls, or columns which are to connect the package to the PCB or IC socket. The bottom side conductors 28 can be integral to the package, or can be provided by or assembled using a solder column or balls.
The body of the package 22 provides, among other things, routing of the top side conductors 26 to the bottom side conductors 28. In complex IC designs, the die 20 may have thousands of interconnect sites (i.e., solder bumps) thereon, while the package 22 accordingly has thousands of top side conductors 26 and bottom side conductors 28. Further, the package 22 may be comprised of multiple layers (i.e., twenty or more) of ground planes, power planes, or signal distribution layers, which are used to route the connections between the top side conductors to the bottom side conductors.
As recognized by the present inventors, it can be very difficult and time consuming to design the logical and physical connections between the top side conductors 26 to the bottom side conductors 28, particularly where relationships such as electrical and physical constraints between the groups of signals lines need to be maintained throughout the package, as with the case of very high frequency signal lines. Such logical connections are conventionally designed by a package engineer using manual data entry to manually connect each top side conductor to each bottom side conductor—such as by manually “pointing and clicking” between two conductors within a software design tool. While commercially available design tools can automatically assign these connections, such tools have severe limitations in their ability to follow the required electrical and physical design constraints.
As recognized by the present inventors, what is needed is a method for automatically routing the connections between top side conductors and bottom side conductors of an IC package, while maintaining the relative relationships between groups of signal lines as needed.
It is against this background that various embodiments of the present invention were developed.